Conduit Bike Trailer





Introduction: Conduit Bike Trailer

Build a nice bike trailer out of a piece of electrical conduit and some old bike bits

Step 1: What You Need

Two bike forks
wheels for the forks
A piece of 10' steel electrical conduit that can fit (snuggly-ish)over the head of the bike fork. 1" conduit worked for me
A piece of thinner conduit, also steel. This is to make a brace or two
A sturdy piece of wood. I initially used a broomstick, which prompty shattered. A 2x3 worked (and is still working...)
Two old bike inner tubes. Get these from the dumpster behind a bike store, or your enemies' bikes

the plumbing pipes in the picture have nothing to do with the project--they're just living their lives, not bothering anybody, so I say, live and let live, right?

Step 2: Ways to Build It

I can think of three ways to assemble this, all of which would work pretty well.
The differences are how you attach the bits of conduit to one another.

You could:
Lash with inner tubes

I used a MIG welder, because I wanted welding practice. If you wanted to bolt instead, every time I weld two pieces together, you would drill a hole through them and stick a bolt through it. You'll probably want to whack the conduit a bit where you'll be drilling to flatten it out.
If you're lashing, then just lash, man.

If you're welding, be sure that you don't have galvanized conduit. Seriously--welding galvanized steel frees criminal molecules that had been locked up in their metallic prison, and the criminal molecules run through the air into your lungs and try to kill you. So seriously, don't weld galvanized stuff.

also, if you're welding, make sure all your conduit is steel. Otherwise it probably won't work.

Step 3: Bend the Conduit.

Take the 1" conduit, and bend it to make a
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kind of shape. There are several instructables on how to bend tubing. I tried to cheat and shape my tubing around a restaurant's oil drum, and ended up crimping it by mistake, but the conduit's still strong in the direction that it will get stressed.

Here's Ricketts, modeling with the bent conduit. It's really an ugly bend. I'm sorry :(

Step 4: Attach the Forks

Take your bike forks (keep the wheels off them for now) and stick them into the open ends of the conduit. Use your preferred method of attaching them. Take a second to make sure they're aligned with eachother, and that they're perpendicular to the ground.

Step 5: BRACE!

Use a hacksaw, pipe cutter, or grinder to cut a piece off the other conduit that will brace across your frame. Attach it near the wheels.
The picture's pretty self-explanatory, I think

Step 6: Lengthwise Thingy

Now, cut another piece of conduit that can run length-wise. This isn't very structural, but it's handy to attach things to them when you want to trail around.
Attach it down the center of the frame.

I made mine really long originally, thinking that I could use it as the tongue that attaches to the bike. Then I remembered that conduit can bend pretty easily and cut it off at the top of the frame

Step 7: Put the Wheels On

put the wheels on
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put the wheels on

Step 8: La Lingua

The tongue is the piece of wood that will attach to your bike. You probably want 3 feet or so between the bike and the trailer, and then overlap a couple of feet (or more!) with the conduit running down the center of the frame.
Use a piece of inner tube to lash the tongue to the conduit.

Step 9: Attach It to Da Bike

Now, attach the tongue to your bike seat with another inner tube. Lash it tightly.

Step 10: Done!

sweet, you're done
Go bike around and haul things.
I'm pretty sure I wouldn't trust it with a human's weight, but I used this trailer to carry my laundry to and from the laundromat, and also to shlepp 2 4x8 sheets of plywood a couple of miles, and it's worked really well so far.


alex hornstein



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    Breathing in the fumes from welding galvanized steel and iron doesn´t kill you it only makes you sick enough to wish it did. Here in sweden its called "Galv-frossa" which means literly the "galvanized-shakes" but a better expression would probably be "the Zink-shakes" beacuse its the fumes from the heated Zink-layer that is the culprit. Its quite common among foundry/steel-workers who work with galvanised steel here in sweden and they supossedly build up an immunity to the shakes over time.

    In the US, it is usually called zinc shakes. It may be mild and a few minutes walking it off might do. But it can be quite serious and I am in favor of calling an ambulance just in case. I really doubt that anyone become immune to it. I suspect that most people who weld get smarter and use better ventilation after they get a mild dose of zinc shakes.

    Yeah, but if you're in an area with crappy ventilation, I heard it can wreak havoc with your system. An interesting thing a friend was telling me--In the US, Galv-frossa is called Monday Night Fever. Professional welders can get a tolerance for zinc fumes over time, so during the week, when they are constantly exposed to fumes, they are pretty immune to it, but over the weekend, their tolerance drops back down, so they all get sick monday night. The first time I welded, I got horrible flu-like symptoms within about an hour. I was welding bike tubing, so I still don't know what caused it, since I don't think that it's galvanized. Maybe I missed some paint when I was grinding a clear spot to weld, and breathed paint vapors. Anyway, it sucked.

    I've not done much with innertube lashing, so I don't know how much friction it would provide for the hole here. I was thinking you might want to drill a hole 6" or so from the end of the wood (6" from the front), and put a nail (with the point filed/ground off) through it. You could bend a rounded 90 degree angle into it, so it could hook around your seatpost a bit. This might be a good idea (especially with heavier loads).

    I have lashed with inner tubes and they can be quite strong. Usually, you'll need more inner tubes than you would expect to use.

    I've pulled ~300 pound loads with innertube lashings without a problem. Innertubes have so much friction that they can hold pieces together incredibly well. Just be sure to lash them tightly

    That's quite a substantial load. I was seriously considering building one of these, but I'm in a dorm building on a college campus, and my spare bike parts are at home, so I don't have them with me and I have no place to store it.

    And then, a few months ago, my bike got stolen. It was right after I put on the chrome fenders that I had brought back from the junk bike I bought in Japan when I was there, too. But other than that, it didn't have much worth left to it other than being an abusable college-student bike (front derailer=gone, rear derailer=3 or 4 gears, instead of 5, depending on its mood, rear brake=gone, a spoke or two on the rear wheel=gone, tires and most of the non-painted parts=crapped up and nasty from the better part of a year and a half of sitting outside through rain, snow, freezing cold, boiling heat).

    I miss it though. I do a lot of walking now. I loved riding in snow last winter.

    if you don't want to weld the forks into the frame, how else could you do it securely? i'm thinking of making a trailer similar to this, but out of pvc pipe. i don't know how to keep the forks secure, though.

    I'd drill a hole through the fork and the pvc pipe, line up the holes and throw a bolt through them with some nice wide washers and a lockwasher to keep the nut from coming loose

    You might want to try a nylon type of nut with the steel threads. I believe they are called nylock nuts.